Machine for polishing masonry floors

ABSTRACT

A wheeled carriage carries an electric motor the shaft of which is connected by belts to drive two vertical driven shafts in opposite directions. Meshing gear-shaped polishing wheels on the lower ends of these shafts have abrasive stones on their lower surfaces. The shafts extend through pillow blocks which are mounted on arms extending from the carriage, the support for each pillow block being in the plane of the associated driving belt to prevent turning moments from being exerted on the driven shafts by the belts. The wheels may be adjusted toward and away from the polishing wheels to vary the pressure of the abrasive stones on the floor.

0 United States Patent 1 [111 3,721,048 Rand 1March 20, 1973 [54] MACHINE FOR POLISHING MASONRY 2,793,476 5/1957 Lombardo ..51 177 FLOQRS 3,098,329 7/1963 Doran ..51/177 [75] Inventor: Sidney Rand, Rio Piedras, Primary Examiner otheu M Simpson [73] Assignee: The Goverment of the Common- Attorney-Scrivener, Parker, Scrivener & Clarke wealth of Puerto Rico, as representative of all the People of Puerto Rico ABSTRACT 22 Filed; Oct 2 197 A wheeled carriage carries an electric motor the shaft of which is connected by belts to drive two vertical PP 192,197 driven shafts in opposite directions. Meshing gearshaped polishing wheels on the lower ends of these 2 .s. Cl. ..51 174 Shafts hm abrasive smnes their surfaces- E B24) zgloo The shafts extend through pillow blocks which are mounted on arms extending from the carriage, the [58] Field of Search ..51/174, 177 pp for each pillow block being in the plane of the associated driving belt to prevent turning moments [56] kefe'ences from being exerted on the driven shafts by the belts. UNXTED STATES PATENTS The wheels may be adjusted toward and away from the polishing wheels to vary the pressure of the abra- 1,571,571 Cavicchi ..51/177 ive stones on the floor 1,601,087 9/1926 Simpson..... ..51/177 X 1,919,389 7/1933 5 Claims, 3 Drawing Figures Myers ..5 1/177 PAIENIEnmzo ms 3.721. 048

/ INVENTOR SIDNEY RAND 1 Ill M- II I 'll MACHINE FOR POLISHING MASONRY FLOORS DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the floor polishing machine provided by the invention:

FIG. 2 is a vertical sectional view through the machine; and

FIG. 3 is a sectional view taken on line 3-3 of FIG. 1.

DESCRIPTION OF THE INVENTION The improvement provided by this invention is a floor polishing and grinding machine using much higher abrasive velocities and being of much lighter weight than similar machines for the same purpose currently in use, resulting in much higher abrasive efficiency, superior quality of finish, and lower labor costs in the floor polishing and grinding operation, whether of terrazzo, marble, concrete or any similar material. It is difficult to achieve high abrasive velocities with machines of conventional design because the lubrication and excessive weight problems complicate the use of gear drives, while the conventional apparatus for achieving flexibility of the plane of grinding for the abrasive proves unsuitable for the higher speeds of revolution required.

The structure of my improved machine makes possible the use of belt drive and provides improved flexiblity to the position of the grinding discs and the pressure exerted by them on the floor. The result is a lightweight machine which is easy to build and maintain in operation with a much higher grinding efficiency than known machines, both with respect to labor cost and product quality.

A machine constituting a preferred embodiment of my invention is disclosed in the drawings and comprises a carriage having a frame designated generally at 2 and consisting preferably of side plates 4, 6 which are spaced apart laterally of the direction of movement of the machine when in use, and having an upwardly and rearwardly'extending handle 8 by which the machine is guided and, in some cases, propelled. The two side plates of the frame support between them an electric motor 10 the armature shaft of which extends vertically downwardly from the motor and has fixed to it two sheaves l2, 14. A cable extends from the motor for connection to a source of electric power. The frame and the motor carried by it are made mobile by wheels 18, which are supported, respectively, on the lower parts of the side plates 4, 6.

An important feature of the invention is the provision of means by which the wheels may be adjusted fore and aft of the machine, and in the disclosed embodiment of the invention these means are provided by a series of holes 22, extending along each side plate adjacent the lower edge thereof and adapted to register with any of a series of holes 24 formed in a bracket 26 which supports each of the wheels. It will be apparent that the position of the bracket may be adjusted to a desired position fore and aft of the machine and then held releaseably in this adjusted position by bolts put through the registering holes 22, 24. The motor 10 is, of course, fixed to the frame and the described means therefore permits adjustment of the wheels with respect to the center of gravity of the motor and frame assembly, for a purpose and with a result which will be described.

Means are provided by the invention for engaging and polishing and grinding the floor, and for driving these means from the motor 10. Such means comprise, first, two connecting arms 30, 32 which are connected, respectively, at or adjacent their one ends to the side plates to the side plates 4, 6 of the machine frame and which extend therefrom in the direction of forward movement of the machine. Each of these arms is attached to its side plate by a pin or shaft 34 which extends through registering holes in the side plate and the connecting arm to permit pivotal movement of the connecting arm with respect to the machine frame.

Adjacent the outer ends of the two connecting arms 30, 32 there are provided the means for supporting and driving the two rotatable grinding discs 40, 42 which rotate in horizontal planes with their lower surfaces in engagement with the floor. The grinding discs are attached, respectively, to the lower ends of vertical shafts 44, 46, to the upper ends of which are attached, respectively, the driving sheaves 48, 50. These sheaves are connected by endless belts 52, 54 to the two sheaves 12, 14 on the shaft of motor 10 and it will be seen that one belt is crossed with respect to the other so that the shafts 44, 46 and the polishing discs will be driven in opposite directions of rotation.

Each of the shafts 44, 46 is supported on its associated connecting arm 30 or 32 in the same manner, and only the supporting means for shaft 46 will therefore be described. This means is particularly illustrated in FIGS. 2 and 3 and comprises, first, a pillow block 60 which provides a bearing for the shaft 46 and to the exterior of which is attached a vertical plate 62 from which there extends a pin 64 which is rotatably received within a bearing in connecting arm 32. This pin is positioned in the horizontal plane of the driving belt 54 as shown in FIG. 3.

As each pillow block is connected to its associated connecting am by means located in the horizontal plane of the associated driving belt, no moment of force can be exerted on either of the shafts 44, 46 by tension of the driving belts. If the pillow block bearing is made self-aligning, additional flexibility is achieved. However, the radially inward component of belt tension at the sheave produces a moment on the driving shaft which, in turn, will produce either forward or backward thrusting by the stones on the floor, acting in the same direction rather than cancelling each other. The machines thus become self propelled, switching direction simply by changing rotation of the drive motor.

Each of the grinding discs 40, 42 is flat and gearshaped, andthe two intermesh, as shown in FIG. 1, and have grinding stones 70, rotatably mounted on their lower surfaces. As the two discs rotate at the same speed and in opposite directions and no force need be transmitted from one to the other, their relative velocities in the areas where they mesh is low. For this reason there is no danger of damage caused by one disc striking the other, nor is there any need for lubrication between the discs.

The connection of the wheels to the motor and frame through adjustable means permits the wheels to be adjusted in position fore and aft of the machine and of the center of gravity of the motor, and it will be apparent that by making a desired adjustment of the position of the wheels the effective pressure of the weight of the motor on the grinding discs may be varied, as the wheels act as a fulcrum point between the motor and the discs.

To increase pressure on the abrasive stones the wheels are simply moved back, increasing the moment caused by the weight of the motor. To decrease pressure the wheels are moved forward.

lclaim:

1. A floor polishing machine comprising a carriage supporting wheels for the carriage, an electric motor mounted on the carriage with its armature shaft vertical, two sheaves mounted on the motor shaft to rotate therewith, two spaced substantially parallel arms extending outwardly from the carriage in the direction of movement thereof, a pillow block on each arm adjacent the outer end thereof, a rotatable vertical driven shaft journaled in each pillow block, a horizontal polishing wheel mounted on the lower end of each driven shaft, a sheave on each driven shaft, an endless driving belt connecting each of the motor shaft sheaves to one of the driven shaft sheaves, the belts being crossed with respect to each other whereby the driven shafts and polishing wheels are rotated in opposite directions.

2. A floor polishing machine according to claim 1, comprising in addition means for adjusting the position of the supporting wheels toward and away from the polishing wheels and with respect to the motor.

3. A floor polishing machine according to claim 1, in which each of the polishing wheels is gear-shaped and the two wheels are meshed at their peripheries.

4. A floor polishing machine according to claim 1, in which the connection between each pillow block and the arm supporting it is in the plane of the belt driving the shaft journaled in the pillow block.

5. A floor polishing machine according to claim 1, in which the arms, the driven shafts journaled on them, and the polishing wheels on the driven shafts, are mounted on the carriage on horizontal pivots for vertical rocking movement. 

1. A floor polishing machine comprising a carriage supporting wheels for the carriage, an electric motor mounted on the carriage with its armature shaft vertical, two sheaves mounted on the motor shaft to rotate therewith, two spaced substantially parallel arms extending outwardly from the carriage in the direction of movement thereof, a pillow block on each arm adjacent the outer end thereof, a rotatable vertical driven shaft journaled in each pillow block, a horizontal polishing wheel mounted on the lower end of each driven shaft, a sheave on each driven shaft, an endless driving belt connecting each of the motor shaft sheaves to one of the driven shaft sheaves, the belts being crossed with respect to each other whereby the driven shafts and polishing wheels are rotated in opposite directions.
 2. A floor polishing machine according to claim 1, comprising in addition means for adjusting the position of the supporting wheels toward and away from the polishing wheels and with respect to the motor.
 3. A floor polishing machine according to claim 1, in which each of the polishing wheels is gear-shaped and the two wheels are meshed at their peripheries.
 4. A floor polishing machine according to claim 1, in which the connection between each pillow block and the arm supporting it is in the plane of the belt driving the shaft journaled in the pillow block.
 5. A floor polishing machine according to claim 1, in which the arms, the driven shafts journaled on them, and the polishing wheels on the driven shafts, are mounted on the carriage on horizontal pivots for vertical rocking movement. 